This invention relates to a radio antenna as a transmitting antenna or receiving antenna and particularly to such antennas for a mobile radio system, and generally to a mobile radio system and particularly mobile station such as cellular phones.
Radio frequencies for radio communication begin in a frequency range of a few kHz. For the transmission of radio broadcasts, for example, frequencies between 520 kHz and 1,605.5 kH are used in the medium wave range; in the short-wave range frequencies between 5.9 MHz and 26.1 MHz, and in the ultra-shortwave range between 87.5 MHz and 108 MHz. For the transmission of television broadcasts, frequencies between 124 MHz and 790 MHz are used.
Ultra-high frequency ranges are used, among others, for mobile telephones with analog technology from 450 MHz to 465 MHz, and for the digital GSM (Global System for Mobile Communication) from 890 MHz to 960 MHz and 1,710 MHz to 1,880 MHz. Wireless telephones operate in a frequency range above that, from 1,180 MHz to 1,900 MHz. These ultra-high frequencies allow the use of relatively small antennas and guarantee a comparatively reliable connection for mobile communication.
Directional microwave connections currently use frequencies between 2 GHz to 40 GHz.
Radio frequencies are scarce resources and today, all reasonably usable frequencies are practically occupied already. One permanent objective will thus be to better use these limited radio frequencies availablexe2x80x94through improvements in transmission engineering and improvements in modulation engineering for the highest possible rate of information transmission with a good transmission quality.
Furthermore, with regard to radio systems, there is a general demand for a simple, low-cost design, as well as an environmentally sound and the most energy-saving operation. These requirements are to be taken into account especially for a mobile radio system with mobile telephones (cellular phones).
A mobile radio system comprises, in a generally known manner, mobile stations (MS) as cell phones (cellular phones) for subscribers. Furthermore, a mobile radio system comprises base transceiver stations (BTS) each in one local area as a radio cell, with larger local areas divided into adjoining radio cells. The base transceiver stations handle radio traffic with the mobile stations. Several base transceiver stations (BTS) are allocated to one base station controller each (BSC) with which they are connected via data transfer and which control and coordinate the allocated base transceiver stations (BTS). Data transfer can here be done via copper lines or via radio, especially point-to-point radio systems.
Furthermore, several base station controllers (BSC) are in turn allocated to one mobile radio switching center (MSC). Data transfer can here again be done either via lines or via point-to-point radio systems.
For a high level of information transmission, a plurality of different modulation and demodulation procedures is used, such as, for example, the transmission on many small channels of small bandwidth with frequency multiplexing and/or time multiplexing, where howeverxe2x80x94due to transmission inaccuracies and for safeguarding the informational contentsxe2x80x94safety spacings must be maintained, and also especially frequency safety spacings.
With standard antennas, the signal quality while transmitting and/or receiving can be negatively affected, among other things, due to antenna noise since they can be operated only to a limited extent in a frequency-selective manner and only with some sideband noise. This is one reason, among others, why the presently required safety spacings cannot be reduced at will.
Especially for mobile telephones (cellular phones), there is a demand for a low-weight compact design and energy-saving operation. The presently relatively great weight and size of the mobile phones are essentially due to the battery and, among other things, due to the filters for improving the signal quality.
Accordingly, it is one objective of the invention to propose a simply designed radio antenna as a broadband antenna which covers a large utilizable radio frequency range and which can be operated in transmitting and receiving mode with a high frequency-selective precision. Another objective of the invention consists of proposing a mobile radio system with the use of such a radio antenna.
The first objective is solved by the transmitting and receiving antennas as described and claimed herein, and the second objective by the mobile radio system that is described and claimed herein.
In one aspect, the radio antenna of the invention is a planar antenna comprising a carrier part, a coating applied thereto, and of two coating feeders.
The carrier part consists of an insulating material.
The coating preferably is composed of a coating material having the following composition:
a. 48% to 65% amount of substance of a basic substance comprising:
36% to 46% amount of substance binding agent,
12% to 22% amount of substance insulator,
12% to 24% amount of substance dispersing agent,
8% to 40% amount of substance distilled water and
b. 35% to 52% amount of substance graphite, the composition of the binding agent being
64% to 79% amount of substance distilled water,
4% to 6% amount of substance sulfonated oil,
0.16% to 0.24% amount of substance phenols or 0.05% to 0.5% amount of substance benzisothiazolinone,
17% to 22% amount of substance casein,
0.8% to 1.2% amount of substance urea,
2% to 6% amount of substance alkaline thinning agent, and
2.3% to 2.8% amount of substance caprolactam.
Similarly electrically active coating materials are known in connection with radiation heating systems where heating effects in matter are to be produced through frequency emissions in the THz range via molecular resonance phenomena. In contrast, the instant coating material of this invention is especially designed for use in thexe2x80x94in turnxe2x80x94lower-frequency radio antenna range.